Backwall Reflections Research Articles

Ultrasonic testing of plasma sprayed coatings

A study examining the application of ultrasonic testing to plasma sprayed coatings is presented. It is shown that bonding defects in aluminium and molybdenum coated samples can be found using sound in the frequency range 5–10 MHz. Though the transmission method is shown to be effective, the backwall reflection method is shown to be the more sensitive to these defects. It is also shown that the attenuation of 5–10 MHz ultrasound in aluminium coatings is related to porosity.